| The development of miniaturized chemical analysis systems is an important trend in analytical chemistry. Recently, microplasmas have attracted attention as potential detection devices for microfluidic systems because of their small size, reduced gas and power consumption, and relatively low manufacturing cost. In the present dissertation, microplasmas have been investigated to develop new atomization and ionization methods. The main contents of the present dissertation are as follows:1. A novel hydride atomizer for AAS based on atmospheric pressure dielectric barrier discharge (DBD) microplasma has been developed. This atomizer offers the advantages of low operation temperature and low power consumption in comparison with the currently used electrothermal quartz atomization operated at 900 0C with a power supply of several hundred watts. The present technique has additional advantages: small size, easiness for fabrication, and good tolerance to residue moisture. Moreover, results indicated that DBD could be used not only for the atomization of arsine, but also for the atomization of hydrides of MMA and DMA. Thus it was coupled to HPLC for the speciation of arsenic. This atomizer was also extended to the atomization of other volatile elements (Sb, Se, and Sn). Based on this study, a low temperature atomizer for AFS has also been developed and applied for the analysis of As, Se, Pb, and Sb.2. New method for mercury analysis based on microplasma sources has been developed for atomic emission spectrometry. First, a new vapor-generation technique is reported for mercury determination in aqueous solutions. Without need for a chemical reducing agent, dissolved mercury species are converted to volatile Hg vapor using a solution cathode glow discharge. In addition, it is applicable to both inorganic and organic Hg determination and has high generation efficiency. Second, microplasma emission source based on DBD has been developed for the determination of Hg. It offers several important advantages over other emission sources: low power consumption (<1W), small size and ease of fabrication, low gas consumption. The DBD microplasma has a relatively modest gas temperature (N2+ rotational temperature of 578±92K) and low continuum and structured background emission. This simple spectral background suggests that Hg emission could be detected effectively with a simple interference filter. The DBD microplasma is also tolerant of residual water vapor within the sample gas stream, making it attractive for use with cold vapor generation sample introduction. Further, the small plasma dimensions, in-line flow cell style, and high plasma stability make the DBD attractive for use with flow injection strategies. These studies suggest that a portable, miniature, automated atomic emission spectrometer based on the DBD would be attractive for the determination of mercury in the field.3. A novel plasma-based desorption/ionization method that can yield mass spectral information under ambient conditions from a range of surfaces without the requirement for sample preparation or additives is reported. The source is carried out by generating a nonthermal DBD plasma jet which interacts directly with the surface of the analyte. Desorption and ionization then occurs at the surface, and ions are sampled by the mass spectrometer. The technique is demonstrated for the detection of active ingredients in pharmaceutical formulations. It has also been successfully applied to the analysis of nicotine in cigarette, thiosulfates in garlic and caffeine in coffee beans. Moreover, it can be applied to the direct analysis of pesticides on the surface. Without the need for prior sample preparation, solvents, it is a promising technique for high-throughput screening in pharmaceutical or food safety analysis.
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